1. Field of the Invention
The present invention generally relates to a color video printer, such as a cycolor type color video printer, and more particularly to a heat-fixing apparatus for such a color video printer which reliably prevents rollers such as compression roller from being stained with dyestuff of color image on a receiver paper, improves a heat utilization efficiency of a heat source thereof and uniformly performs the heat-fixing operation for the receiver paper.
2. Description of the Prior Art
With reference to FIG. 1 which shows an operational principle of a heat-fixing operation by a known heat-fixing apparatus for a cycolor type color video printer, the cycolor film 2 which is applied with a great number of cylith capsules 1 is exposed, by using a light-exposing apparatus such as a F/O CRT (Fiber Optics Cathode Ray Tube), to an image light corresponding to an optical image which is to be printed on a receiver paper. In result, a part of the cylith capsules 1 which were exposed to the image light are cured owing to a high photosensitivity thereof while the other cylith capsules 1 which were not exposed to the image light remains as in previous liquid state.
Sequentially, a receiver paper 5 comprising a paper base 4 being covered with a resin layer 3 passes through a pair of developing rollers, that is, upper and lower developing rollers 6, under the condition that it overlaps with the light-exposed cycolor film 2. At this time, the cylith capsules 1 which were not exposed to the image light are broken due to a substantially high pressure generating between the upper and lower developing rollers 6 so that the dyestuff of the broken cylith capsules 1 is transferred onto the receiver paper 5. That is, the resin layer 3 of the receiver paper 5 is applied with the dyestuff of the broken cylith capsules 1.
Thereafter, the receiver paper 5 out of the upper and lower developing rollers 6 is heated by a heat-fixing apparatus 7. In result, the resin layer 3 of the receiver paper 5 is fused in order to react upon the dyestuff having been applied on the receiver paper 5, thereby causing the color image to be heat-fixed on the receiver paper 5.
There have been proposed several types of conventional heat-fixing apparatus for a cycolor type color video printer for heat-fixing a color image on a receiver paper in accordance with the above-mentioned heat-fixing operational principle. Hereinafter, two types of conventional heat-fixing apparatus as examples will be described in conjunction with accompanying drawings, respectively.
Referring to FIG. 2 which shows a sectional view of an embodiment of a conventional contact type heat-fixing apparatus for a color video printer, the contact type apparatus comprises a heat roller 12 enclosing therein a halogen lamp 10 as a heat source and being coated at circumferential outer surface thereof with a teflon layer 11, and a compression roller 14 being coated at circumferential outer surface thereof with a silicon rubber 13 and adapted for contacting with the outer surface of the heat roller 12 at a predetermined pressure. In addition, there are provided a pair of separating members 16, each disposed at each roller 12, 14 and adapted for smoothly separating the receiver paper 15 from the roller 12, 14, and an oil supplying member comprising an oil reservoir 17 for containing oil which is to be supplied to the heat roller 12 during the heat-fixing operation, and an oil feeding tube 18 for allowing the oil of the oil reservoir 17 to be supplied to the heat roller 12 therethrough. Therefore, the color image on the receiver paper 15 is heat-fixed during the receiver paper 15 passes through the heat and compression rollers 12 and 14, then the receiver paper 15 out of the rollers 12 and 14 is smoothly separated from the rollers 12 and 14 by means of the separating members 16. At this time, the heat roller 12 is continuously supplied with the oil by means of the oil supplying member 17 and 18.
On the other hand, FIG. 3 shows a perspective view of an embodiment of a conventional non-contact type heat-fixing apparatus for a color video printer. As shown in the drawing, the conventional non-contact type apparatus comprises two pairs of upper and lower feed rollers 21, 22 and 23, 24 disposed such that the two pairs 21, 22 and 23, 24 are spaced from each other pair by a predetermined distance, and the upper and lower rollers 21 and 22, 23 and 24 of each pair contact with each other at a predetermined pressure. In addition, there are provided a halogen lamp 25 disposed between the upper feed rollers 21 and 23 of the two pairs in order to act as a heat source, and a reflector 26 surrounding the halogen lamp 25 in order to concentrate the heat generated by the halogen lamp 25.
In such a conventional non-contact type heat-fixing apparatus, the upper feed rollers 21 and 23 are connected to each other by means of a endless belt 27 wrapping thereabout in order to interlock with each other, thereby feeding the receiver paper 20 so as to pass under the reflector 26. At this time, the receiver paper 20 is supplied with the heat which is generated by the halogen lamp 25 and then concentrated by the reflector 26, thereby causing the color image having transferred on the receiver paper 20 to be heat-fixed.
However, in the conventional non-contact type heat-fixing apparatus as shown in FIG. 3, the heat-fixing apparatus has a substantially lower heat utilization efficiency so that it must be necessary to increase the temperature of the halogen lamp 25 to a substantially higher temperature. In result, the conventional non-contact type heat-fixing apparatus has a disadvantage in that in case of increasing the temperature of the halogen lamp 25 to such a high temperature, it can not reliably provide a stability such as due to occurrence of ignition of the receiver paper 20, occurrence of a danger that the whole system of the apparatus is subjected to an undesirable high temperature atmosphere, and an evaporation of moisture from the receiver paper 20, resulting in causing the receiver paper 20 to be rolled, thus occurring a paper jam.
On the other hand, in the conventional contact type heat-fixing apparatus as shown in FIG. 2, even though it is possible to provide a relatively good stability, it has a disadvantage in that is needs a substantially long warming time for accomplishing a desired temperature for reliably performing the desired heat-fixing operation. In addition, the heat roller 12 of this type of heat-fixing apparatus has to directly and closely contact with the color image on the receiver paper 15, thereby introducing another disadvantage of occurrence of an offset of dyestuff in which the heat roller 12 is stained with the dyestuff of the cylith capsules.